{"id":"CVE-2026-116579","aliases":[],"title":"Autobahn Python: permessage-brotli inflates a whole frame before maxMessagePayloadSize is checked (incomplete fix of GHSA-hxp9-w8x3-p566)","description":"Autobahn Python is a WebSocket and WAMP implementation for Python that supports Twisted and asyncio. From 26.7.1 until 26.10.1, PerMessageBrotli.decompress_message_data in compress_brotli.py calls the Brotli decompressor without an output limit and checks maxMessagePayloadSize only after a complete frame has been inflated. An unauthenticated WebSocket client can send a small, highly compressed frame that allocates hundreds of MiB before rejection, causing memory-exhaustion denial of service on servers that enable the opt-in permessage-brotli feature through the compress extra. Deflate and bzip2 already enforce the remaining output budget and are outside this residual vulnerability. This issue is fixed in version 26.10.1.","severity":"medium","score":5.9,"published":"2026-10-26T20:29:22.906Z","modified":"2026-10-27T14:18:18.772Z","withdrawn":false,"knownExploited":false,"affected":[],"references":["https://github.com/crossbario/autobahn-python/security/advisories/GHSA-pjh6-c8mg-3x7m","https://github.com/crossbario/autobahn-python/pull/1987","https://github.com/crossbario/autobahn-python/commit/a41442bbee4f6126a8ce1bb892840124c24d16f1","https://github.com/crossbario/autobahn-python/releases/tag/v26_10_1"],"sources":[{"name":"CVE","id":"CVE-2026-116579","modified":"2026-10-27T14:18:18.772Z","url":"https://www.cve.org/CVERecord?id=CVE-2026-116579"}],"assessments":[{"source":"CNA","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","score":5.9}]}